It is not the Friday before the conferences as I did not find the time earlier, but now the promised PR to foreman-graphics is here: Add images for Github Profile and Documentation by dgoetz · Pull Request #5 · theforeman/foreman-graphics · GitHub
And as I really want the old architecture image to be replaced, I directly create also Replace the archtitecture image with a newer one by dgoetz · Pull Request #2126 · theforeman/theforeman.org · GitHub
So I would leave adding the feature images to the documentation to @docs as they will know best.
And as we postponed this until now the question is should we generate also a Github profile for Katello in the same style?